Mutational analysis of the envelope gene of Moloney murine leukemia virus.

The env gene products of Moloney murine leukemia virus are required for binding and entry of the virus into the target cell. Thirty-three linker insertion mutations were constructed throughout the env gene of Moloney murine leukemia virus. Twenty of the mutations were located in the surface protein (SU), and the remaining thirteen were located in the transmembrane protein (TM). The viability of the viruses containing these env gene mutations was determined by performing transient transfections and screening for the release of reverse transcriptase. Eleven viable mutants were isolated, nine in SU and two in TM. Three of the viable mutants were temperature sensitive. Four of the viable mutants were clustered in the carboxy terminus of SU. The env gene products of transfected cell lines which produced viable virus were analyzed. Our results indicated two regions of SU important for the stability of the SU/TM heteropolymer and one region important for the interaction of the env gene products with the viral core.